Flat digital image sensor designs with an array of light sensitive pixels, mask layer with an array of micro apertures, and a lens layer with an array of micro lenses superposed on each other, may enable implementation of very thin digital camera assemblies allowing, for example, integrating a digital camera within a display assembly. In such thin and flat digital image sensor, each pixel may have a partial field of view with a width and direction determined by a micro aperture and a micro lens associated with it. The entire field of view of the image sensor may be formed by the partial fields of view of pixels.
Micro lens arrays and mask layers with micro aperture arrays with predetermined positioning of the micro lenses and openings, respectively, may be manufactured with high accuracy. However, imaging performance of a flat digital image sensor may be very sensitive to relative positioning of the mask layer and the pixel array. Even a small deviation from a designed relative positioning may affect the image quality strongly.